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Threatened and Endangered Succulent SpeciesBy Joe Merkelbach

The threatened and endangered succulent species and subspecies on the United States listings include some California dudleyas and agaves from Arizona and the Caribbean.

There are four agave species listed by the Center for Plant Conservation. None are listed as threatened or endangered on the United States list.

Arizona lists A. arizonica as a probable hybrid between A. chrysantha and A. toumeyana var. bella, perhaps evolving into a new species because of its isolated mountainous habitat. A. eggersiana is a species native to St. Croix in the U.S. Virgin Islands, an example of an island that evolved in isolation and has only a small wild population limited by habitat.

The threatened and endangered dudleyas, all crassulas that were until recent taxonomic changes named echevarias, are natives of coastal California. They all share a tendency to grow in locations with reduced long-term water availability -- cliffs, rocks and marine coastal areas where moisture is drawn from fogs and mist.

The two federally endangered Dudleya species are D. setchellii in the Santa Clara valley, and D. traskie on Santa Barbara Island. The Rancho Santa Ana Botanic Garden is the location for all but one of the Center for Plant Conservation dudleyas, but none of them are fully endowed for study and protection.

Some of the dudleyas under the former designation of echevaria are well appreciated plants in horticultural use.

Support of the dudleya plants at the Rancho Santa Ana Botanic Garden as a location of the Center for Plant Conservation seems a good goal for some of the HSCSS conservation funds.